This study will evaluate the safety and effectiveness of a new investigational drug, omapatrilat compared to lisinopril, an angio converting enzyme (ACE inhibitor), in the treatment of hypertension (high blood pressure). Omapatrilat blocks the action of neutral endopeptidae (NEP) and ACE, both naturally occuring substances in the body. Blood pressure may be lowered by blocking the effects of these substances. ACE inhibitors alone are commonly used in the treatment of high blood pressure. The combination of the NEP component with the ACE component may have an increased benefit over ACE inhibitors alone. The purpose of this study is to compare the effect of omapatrilat and lisinopril on blood pressure in patients who are considered salt sensitive. This study is also being done to collect information about any side effects the drugs may have. Approximately 80 subjects at 4 centers located in the U.S. will participate in the study.